Characterization of aerated foods using ultrasonic reflectance spectroscopy Original Research Article

Our objective was to develop an ultrasonic reflectance spectrometer to non-destructively detect changes in bubble characteristics in aerated foods. A theory was developed to relate ultrasonic reflectance spectra to bubble characteristics. Experiments were carried out using foams with different bubble concentrations and sizes prepared by mechanical agitation of a viscous aqueous solution (1.4% xanthan and 8% whey protein). The complex acoustic impedance of the foams was calculated from measurements of their ultrasonic reflectance from 1 to 7 MHz. The acoustic impedance spectra varied with bubble size and concentration in a manner that was qualitatively predicted by the theory. Our results show that ultrasonic reflectance spectrometry (URS) is sensitive to changes in bubble size and concentration of aerated foods, but that more work is needed to do this quantitatively.